Insulator for underground electric con ductors



NQ Model.)

J. P. MARTIN. f

INSULATORPOR UNDERGRUUND ELECTRIC CODUGTORS. No. 286,947, Patented Oct. 16, 1883.

N. pETERs Pmmrumugmplmn washington. D. C.

Nrrnn STATES 'ATENT miren.

JOHN F. MARTIN, OF CHICAGO, ILLINOIS.

SPECIFICATION forming part of Letters Patent No. 286,947, dated October-16, 1883.`

Application filed March 1:2, 18S-3.

To all whom L may concern:

Be it known that I, JOHN F. MARTIN, acitizen of the United States, residing in Chicago, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Insulators for Underground Electric Vi res, of which the following is a specification.

This, invention relates to improvements in means for'insulating and supporting the electric conductors of an underground system, and has for its object to provide a durable and efficient construction of insulator which can be readily introduced into or removed from the conduit; to provide for supporting and insuto admit of the wires being drawn through the insulator as required or taken out when necessary, and, finally, t0 prevent induetionand all disturbance heretofore incident to` such common failings in underground systems.

To such end my invention consists in an insulator constructed as hereinafter fully described, and illustrated in the annexed drawings, in which- Figure l represents two sections of a conduit-pipe coupled together and inclosing two of my improved insulators, shown coupled and partly in section. Fig. 2 is an end view of one of the insulators fitted within a conduit-pipe. Fig. 3 shows, partly in section, a portion of one of the insulators.

The insulator consists of a block or section, A, composed of asphaltum or asphaltum cement molded int'o cylindrical or substantiallycylin- 3 5 drical form,with a series of longitudinal bores,

B, running from end to end. These bores or perforations are arranged in parallel lines,

and constitute continuous individual wirechambers for the electric wires when the locks or sections are joined. As it is designed that a separate chamber shall be provided for each individual wire, the number vof chambers should, therefore, be equal to the greatest number of wires which will be required. The insulators A are made inthe form of cylindrical sections, and as a means for supporting the same within a conduit-pipe, and also for preventing the 'insulator from turning during or after its introduction into the conduit, I provide each insulatorrwith lon.- gitudinal ribs or tongues C, adapted to fit in lating from each other a large number of wires,

(No model.)

grooves formed in ribs D, which run along the inner wall of the pipe.

In Fig. l I have shown a pair of my perforated insulatorsl coupled together by means of 5 5 short tubes. which are fitted at their ends into the perforations in the blocks, so as to render the passages for thewires continuous throughoutthe line. As more clearly shown in Fig. 4, the diameter of each one of the passages B is enlarged at its end, so as to form a seat, B', for the coupling-tube, which, being fitted in said seat, will thereby connect the passages of adjacent insulators.

In coupling the insulators together the tubes E are fitted in the seats B in the insulators and a space left between the opposing ends of the latter. This intervening space is then filled with asphaltum or other cement, which process can be effected by temporarily arranging a band or easing over the ends of the insulators and the tubes rbetween the two, so as to hold the cement in place until it has set. In this way a filling, F, of cement can be placed between theends of the perforated insulating- 7 5 blocks, so as to connect them together, and also embed the coupling-tubes and form airtight joints. In Fig. 3 I have shown each passage provided at its end with two seats, the outer one of which is somewhat larger in di- 8o ameter than the inner one. This arrangement is preferably adapted where bends occur in the line and it becomes necessary to provide bent passages for the wires. In this instance the tubes E are fitted in the smaller seats Bf, and upon these tubes are fitted the flexible coupling-tubes G, which latter are also rcceived in the seats B2 at the ends of the passages thnough one of the insulators. By thus arranging the coupling-tubesl E and G close ljoints will be formed and the tube G be allowed to be bent according to the direction in which the wires are to be carried. These bends occur at branches along the main, or at drawingin 'boxes or distributers, and at all such points couplings, as herein shown, can be provided. The asphaltum employed for forming these perforated insulators can be combined with any suitable` material and then molded into the required shape, and after hardening it will be found that wires can be ICO introduced and passed through passages B of e escom considerable length, and hence that each insulator A can be niade quite long, if desired, which will avoid the too frequent occurrence of couplings along the line.

Boxes or tra-ps will in practice be connected With the conduit at intervals for the purpose of allowing the Wires to be laid, taken out, or inspected.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, is

l. The combination, with a conduit-pipe, of the perforated asphaltuin insulator in sections, joined together so as to form continuons individual wire-chambers, and iitted within JOHN F. MARTIN.

Vitncsses XV. NV. ELLIOTT, Crus. G. PAGE. 

